Filtering assembly including a multiplicity of interconnected plenum chambers

ABSTRACT

AN AIR-FILTER ASSEMBLY IS FORMED FROM A MULTIPLICITY OF INTERCONNECTED IDENTICAL UNITS EACH HAVING A PLENUM CHAMBER WITH A FRUSTOCONICAL OR FRUSTOPYRAMIDAL HOUSING CLOSED AT ITS NARROW END AND TERMINATING AT ITS BROAD END IN A FILTER CELL, AN INLET PORT AND AN OUTLET PORT FOR AIR TO BE FILTERED EXTENDING LATERALLY FROM OPPOSITE SIDES OF THE HOUSING. THESE UNITS ARE INTERCONNECTED BY THEIR INLET AND OUTLET PORTS INTO AT LEAST ONE LINEAR ARRAY WHOSE PORTS ARE SUCCESSIVELY TRAVERSED BY COMPRESSED AIR FROM A BLOWER WORKING INTO THE FIRST INLET PORT OF EACH ROW.

Jan. 12-, 1971 v 3,553,941

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Jan. 12,1971 3,553,941

-- HANS'JOACHIM WITTEMEIER ET AL FILTERING ASSEMBLY INCLUDING AMULTIPLICITY OF IN'TERCONNECTED PLENUM CHAMBERS 4 Sheets-Sheet 2 FiledFeb.

Hans+Joiachim WI'P'LLI'ILlLLZf.

Gerhard Maui Ill-JUN,

In venlar:

Jan. 123971 Filed Feb. ,5. 19 9 7 3,553,941 HANE'FJOACHIM WITTEMEIERETAL FILTERING ASSEMBLY INCLUDING A MULTIPLICITY OF INTERCONNECTEDPLENUM CHAMBERS 4 Sheets-Sheet 5 Hans-Joachim WITlEi'iEIER Gerhard MaxNLUILANN //7ven for BY 11* M Jam-12,1971

HANS'JOACHIM WITTEMEIER FILTERING ASSEMBLY INCLUDING A MULTIPLICIT-Y OFINTERCONNECTED PLENUM CHAMBERS Fild Feb 5, 1969 4 Sheets-Sheet 4 I I 1WWW IIIHHH'E I I HI 2 Fig. 8

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Hansfllouchim vllTl'Li'lLl ER Gerhard Max Nl'jbi'llkllil In van [or BY Imay PM United States Patent Olfice FILTERING ASSEMBLY INCLUDING A MULTI-PLICITY OF INTERCONNECTED PLENUM CHAMBERS Hans-Joachim WittemeierandGerhard Max Neumann,

Berlin, Germany, assignors to Delbag-Luftfilter Gesellschaft mitbeschrankter Haftung, Berlin, Germany, a corporation of Germany FiledFeb. 5, 1969, Ser. No. 796,832

Claims priority, application Ggrmany, July 15, 1968,

Int. Cl. B1d 46/12 US. Cl. 55-473 9 Claims ABSTRACT OF THE DISCLOSUREThe invention concerns a filter plant for separating suspended materialsout of an air flow or gas flow, preferably for the ventilation of roomswhich are to be kept clinically clean.

Working rooms, such as are necessary in the sphere of space travel,electronics, biology and medicine, must be kept biologically clean, andmust therefore be supplied with air which has 'been conditioned. Thefiltered air flowing into the clean room has a slight excess pressure incomparison with the outside air, in order to prevent the entry ofexternal air at likely leak spots, e.g. at windows and doors. The airsupplied must furthermore, as a compression flow, ventilate the entireworking area, in order to carry immediately out of the working zoneparticles of dust produced in the work operations. In order to sup plyair which is free from dust and germs to these rooms, known asbiologically or clinically clean rooms, an airfiltering plant isnecessary which satisfies the requirements set out and producesan'approximately laminar air flow, i.e. one which has low turbulence,while insuring the necessary air purity.

Filter plants of this type are known wherein along a wall or the ceilingof the room, a plurality of single filter cells, are arranged togenerate an air flow which penetrates through the room as a transverseor descending stream. In known filter plants, the filter wall is formedby box-like plenum chambers, arranged in juxtaposed and superimposedrelationship, in which the separate filter cells or filter packs aresealingly inserted. The rear end of each plenum chamber is as a ruleconstructed as an entrance port supplied from a pressure-dependent,controllable blower which aspirates the previously cleaned andconditioned air from an air-conditioning plant and passes it to theclean working room through the filter cells or filter packs sealinglyinserted in the housings of their plenum chambers. The housing elementsin this at rangement are as' a rule constructed in such a way that theycan accommodate at. most up to four square filter cells 610 mm. longalong the edge and 150 mm. or 292 mm. thick, arranged one above theother, and three filter cells arranged next to one another in numberssufficient to fill the width of the room. The disposable filter cellsinserted in the box elements have the task of cleaning the air flow to ahigh degree of purity. The air issuing from Patented Jan. 12, 1971 thefilter cells of the several plenum chambers passes through the work roomin an approximately laminar transverse flow.

The main problem with these known filter-wall structures, consists inreliably sealing off the separate filter cells in relation to thehousing elements. Further problems occur in the mutual sealing of thehousing elements and the sealing of the filter wall against the floor,ceiling and side walls of the work room. Since the individual filtercells can be inserted in the box-like housing elements, each individualfilter element requires correspondingly designed pressure members, withwhich the edges of the filter cells, equipped with sealing means, arepressed against the sealing strips arranged on the housing. Bearingpressures of the order of 1 to 2 metric tons are necessary for reliablysealing off the individual filter cells in the housing element. In thisconnection it is necessary on the one hand to equip the filter cellswith a frame which can withstand these pressures, and on the other handto provide a suitable supporting structure. With a work room of averagesize, having a working volume approximately 150 m? and 2.50 m. high,approximately 125 filter cells with an edge length of 610 mm. areneeded; this means that, for reliable sealing of the filter cellsagainst the surrounding housing element, 250 to 500 pressure elementsmay be necessary which upon insertion of the filter cells outlay have tobe operated and supervised. The outlay construction of the individualfilter cells and the required presence of pressure elements arecumbersome and the maintenance and supervision costs of the filter wallduring operation are correspondingly high. For the work room mentionedabove, depending on its construction 30 or (with the use of doubleboxes) 15 individual housing elements 2.50 m. high are necessary. Thesehousing elements may have to be specially sealed against one another inorder to prevent the entry of unchecked adulterated air. These sealingproblems encountered with conventional filter walls entail installation,maintenance or supervision costs. The object of our present invention isto overcome these disadvantages and to produce an airfilter system whichmeets the requirements for clinically or biologically clean rooms and inwhich the leakage problem is substantially solved in that the previouslynecessary sealing surfaces and pressure inserts are completely omitted.

This is achieved in accordance with .the invention in that each filtercell spans the base of a tapering housing wall constituting a plenumchamber, the narrow end of this chamber opposite the base being closed.The filter cell is in fluidtight peripheral contact with this housingwhich is provided at two oppositely sloping lateral surfaces with a pairof coaxially disposed conduits serving as inlet and outlet ports which,when joined to complementary ports of adjacent units, form a manifoldfor the delivery of the air tothe several plenum chambers terminating atthe closely juxtaposed filter cells.

By the arrangement in accordance with the invention of each filter cellin a preferably four sided pyramidal or frustopyramidal housing, whichmay be designed as a disposable part, the separate filter cells areaccommodated in gastight fashion in their housings already duringmanufacture, by casting or glueing, so that multiple and expensivesealing measures are no longer necessary. The individual housings can bejoined together by means of the interconnected laterally projectingconduits, in series in any desired length as a part of identical units,each row or every two or three rows being provided with a common blower.The rows of filter housings produced in this way can be arranged in anyhorizontal or vertical array in order to produce a filter Wallsatistying the spacial dimensions. Since the lateral surfaces ofjuxtaposed four-sided housing frames accommodating the filter cells canabut against each other on being joined together, of these housings canbe sealingly interconnected, if necessary, by strips of adhesive.

The interconnected parts of the adjacent housings in a row can also besealed off in a simple way. The advantage of the filter plant inaccordance with the invention accordingly consists in the simplificationof the sealing problems and in a cost saving by the low outlay forequipment. The disposable housings can be manufactured of sound-mufilingmaterial, or coated with such material. Their tapering shape and theabrupt cross sectional change also help prevent the spread of sound.

If the flow of air issuing from the filter wall is not to penetrate theentire work room but is to be discharged at a certain location of thatroom, the plenum chambers and their manifolds may be symmetricallyduplicated on opposite sides of the array of filter cells 'whereby anentrance manifold and an exit manifold are formed upstream anddownstream, respectively, of these cells. In this embodiment also, theconfronting plenum chambers of each unit need not have square orrectangular bases, as in a continuous planar array, so that theirhousings can be of frustoconical rather than frustopyrimidal shape.

We shall now describe various embodiments of our invention withreference to the accompanying drawing in which:

FIG. 1 shows diagrammatically an installation according to our inventionarranged on one wall of a room;

FIG. 2 shows diagrammatically a similar installation arranged on theceiling;

FIG. 3 shows on a larger scale two housings connected to each other,each accommodating one filter cell of an assembly as illustrated in FIG.1 or 2;

FIG. 4 shows a housing in a further embodiment;

FIG. 5 shows a top view to FIG. 4;

FIG. 6 shows a side view to FIG. 5;

FIG. 7 shows on a larger scale in section a housing accommodating onefilter cell;

FIG. 8 shows a variation of the construction of FIG. 7;

FIG. 9 shows a further variation of the construction of FIG. 7;

FIG. 10 shows two housing units connected together, each consisting oftwo frusto-conical housing parts; and

FIG. 11 shows the construction of FIG. 10 on a larger scale.

FIG. 1 shows a filter wall arranged at one side wall 19 of a work room.The filter wall is constituted by four frustopyramidal housings 2, withfilter cells 1, arranged one over the other between an intermediateceiling 17 and a floor 18 of the work room. The housings areinterconnected by ports 3 and 4. Air from an air-conditioning plant (notshown) passes through a pipe 14 and a blower into the interconnectedconduits 3 and 4 of the housings or plenum chambers 2. The air issuesfrom the filter cells 1 in an air flow directed uniformly over theentire room, more precisely in an approximately laminar air flow which,since the chambers 2 are closed at the narrow end of the frustopyramid,passes through the work room as a transverse flow in the direction ofthe lower arrows. Depending on the breadth of the room, several rowseach formed of four superposed housings 2 can be arranged side by side,each row being supplied with air through an individual blower 15.

'FIG. 2 shows a filter wall similar to that of FIG. 1 installed in theintermediate ceiling 17. The air issuing from the filter cells 1penetrates the work room as a descending flow.

'In the filter walls in accordance with FIGS. 1 and 2 the outlet port 3of the last housing of the row is closed in an airtight fashion by acover, not shown.

FIG. 3 shows two connected housings 2. The inlet port 4 of each housing2 terminates in a sleeve 6 representing a female coupling into which thefree end of the outlet port 3 of the adjacent housing 2 is inserted, asa mating rnale coupling, in sealed relationship.

FIGS. 4 to 6 show another embodiment in which the conduits 3, 4 areforeshortened in relation to the frame part 5 (FIG. 7) of the housing .2receiving the filter cell 1. In this embodiment the conduits 3, 4 arejoined to complementary connecting pieces of the adjacent housings 2 bymeans of bellows 7 acting as expansion joints. FIG. 5 illustrates thebase of the frustopyramidal housing as square.

In the embodiment of FIG. 7, the base of housing 2 accommodating thefilter cell 1 has a rim 5. A gastight packing 12 inside rim 5 seals thefilter cell 1 against its mounting frame 21. In this embodiment thefilter cell is shown to consist of a rough filter 10 and a fine filter1 1. For adhesively bonding the filter cell 1 to the housing rim 5 asuitable cast mass is poured into the space lying above the packing 12.

In accordance with FIG. 8 the housing 2 has a flangelike peripheralshoulder 20; the mounting frame 21 of the filter cell 1 is glued in agastight fashion to the edge 20.

FIG. 9 shows another embodiment in which there is a recess 22 around theinside of the mounting frame 21. Edge 20 of the housing engages in thisrecess. The filter cell 1 is fixed to the housing 2 by a cast mass 13 onthe edge 20.

FIGS. 10 and 11 show another embodiment in which each unit includes twofrustoconical housings 8 and 9. Between them these parts enclose thefilter cell 1. Both housings parts 8, 9 have ports 3, 4 which areconnected to adjacent units. The air to be filtered is supplied from theair-conditioning plant through a pipe 14 via a blower 15 into the ports3, 4 of the upper housings 8, penetrates the filter cells 1 and passesthrough the ports 3, 4 of the lower housings 9 into a pipe 16 throughwhich the filtered air is supplied to a predetermined location of thework room. Thus, the two sets of conduits 3, 4 form an entrance manifoldand an exit manifold each communicating with a respective set of plenumchambers above and below the intervening filter cells 1.

We claim:

1. A filtering assembly comprising a multiplicity of identical unitseach with a housing forming a plenum chamber, said housing tapering froman open broad end to a closed narrow end, and with a filter cell placedacross said broad end, said housing being provided on opposite sideswith a pair of coaxial lateral conduits forming an inlet port and acomplementary outlet port; said units being arrayed in at least one rowwith the outlet port of any preceding unit connected to the inlet portof the nextfollowing unit to form a throughgoing manifold communicatingwith said plenum chambers; and a source of high-pressure fluid connectedto the first inlet port forming part of said manifold whereby the fluidissues in parallel from the filter cells of all units thusinterconnected.

2. An assembly as defined in claim 1 wherein said inlet and outlet portsare provided with mating female and male couplings, respectively.

3. An assembly as defined in claim 1 wherein said inlet and outlet portsare provided with expansion joints interconnecting same.

4. An assembly as defined in claim 1 wherein each unit comprises asecond housing substantially identical with the first-mentioned housingand symmetrically disposed with reference thereto on the opposite sideof said filter cell in fluidtight contact therewith, the second housingsof all the units of a row being provided with interconnecting lateralinlet and outlet ports forming a discharge manifold communicating withtheir plenum chambers for receiving filtered fluid from thefirst-mentioned housings by way of said filter cells.

5. An assembly as defined in claim 4 wherein all said housings are offrustoconical shape.

6. An assembly as defined in claim 1 wheerin said housing is offrustopyramidal configuration with a four-sided 6 base at said broadend, the bases of all said units adjoin- 3,412,530 11/ 1968 Cardiff55419 ing one another in fluidtight mutual contact. 3,422,602 1/ 1969 Janson 5 55 14 7. An assembly as defined in claim 2 wherein said bases3,465,666 9/1969 Knab 55484 are square.

8. An assembly as defined in claim 2 wherein each 5 FOREIGN PATENTSfilter cell has a four-sided frame adhesively bonded to the 3425998/1936 Italy 55493 base of the corresponding housing.

9. An assembly as defined in claim 8 wherein said base FRANK LUTTERPnmary Exammer has a projecting rim partly surrounding said frame. B.NOZICK, Assistant Examiner References Cited 10 US. Cl. X.R. UNITEDSTATES PATENTS 55484, 514; 98-40 2,835,341 571958 Parker Jr 555143,360,910 1/1968 Soltis 55484

